There are many biological fluids within our bodies. They include the aqueous humor of the eye, endolymph & perilymph contained within labyrinth of the inner ear, interstitial fluid, milk produced by mammary glands, amniotic fluid, chyme, chyle, gastric juices, lymph, seminal fluid, bile, cerebrospinal fluid and blood. There are a variety of conditions or diseases which result from impaired drainage or directional flow of such biological fluids, and which would benefit from a method to improve the drainage or directional flow. Among such conditions or diseases are, e.g., conditions related to impaired return of the blood to the heart (chronic venous insufficiency), and conditions resulting from impaired lymph flow, which are often referred to as lymphedema.
Chronic Venous Insufficiency
There are several auxiliary physiological mechanisms by which one's heart is assisted in its continuous effort to propel blood through vascular beds. There is the ‘respiratory pump,’ which acts via repetitive inflation/deflation cycles of the chest cavity that leads to a stretch of compliant veins leading to the heart. There is the so-called ‘aortic pump’ or Windkessel effect of the aorta, which helps to propel blood throughout the diastole as a result of elastic recoil. Finally, there is the ‘skeletal muscle pump’, which combats the effect of gravity in upright individuals. The skeletal muscle pump works via compression of nearby veins and requires functionally intact unidirectional valves within those veins.
When the skeletal muscle pump mechanism fails (either due to lack of skeletal muscle activity, distention of veins, failure of venous valves, or a combination of the above), it leads to chronic venous insufficiency, which is also called chronic venous disease (CVD). CVD is one of the most widespread diseases in the populations of the Western world. The number of people who suffer from CVD is very large, with an estimated 25% of adult population having varicose veins, and 6% more advanced chronic disease (Beebe-Dimmer et al., 2005). CVD can lead to chronic skin changes, phlebitis, venous stasis, ulceration and, ultimately, loss of a limb and death. Lower extremity ulcers are particularly common in diabetic patients, with venous disease accounting for majority of them (Greer et al., 2012). In United States alone, the annual cost associated with of CVD treatment is approaching $3 billion, constituting ˜2% of the total health-care budget cost (Robertson et al., 2008).
Today there are several treatments of CVD tailored to specific causes and symptoms. For varicose veins, there are non-surgical options such as sclerotherapy, leg elevation, and elastic stockings. These procedures can be helpful, but they require continuous care and are associated with lower quality of life. Surgical options include vein stripping, sealing veins using radiofrequency or laser energy, or ultrasound-guided foam sclerotherapy. These procedures can be effective, particularly when treating individual vein segments. Downsides of these treatments include high recurrence rate, often at a different site, and surgical complications. Venous leg ulcers are primarily treated using compression, with only 40% to 70% healing after 6 months of treatment (Thomas, 2013). Venous ulcers may get infected leading to cellulitis or gangrene and can eventually lead to amputation.
Impaired Lymph Flow or Lymphedema
The lymph system is a network of lymph vessels, tissues, and organs that carry lymph throughout the body. Lymphedema refers to an accumulation of interstitial fluid due to the insufficient capacity of the lymphatic system. Lymphedema may be inherited (primary) or caused by injury to the lymphatic vessels, in which case it is called secondary. Secondary lymphedema is one of the well-known complications of cancer treatment. It results from the dissection of lymph-nodes and subsequent radiation therapy. It is very commonly observed in breast cancer patients for whom the most common site of the disease is arm lymphedema (Didem et al., 2005). Lymphedema is also common in patients after surgical and radiation treatments of cervical and prostate cancers (Werngren-Elgström and Lidman, 1994). Depending on the surgical procedure, the type of the radiation therapy, and the techniques used to measure fluid accumulation, lymphedema incidence can range from 10 to 90% (Didem et al., 2005; Gärtner et al., 2009). When untreated, lymphedema becomes a chronic condition with the risk of worsening in terms of volume and degree of tissue fibrosis (Casley-Smith, 1995; Petrek et al., 2001). It can lead to cosmetic abnormalities, including limb discoloration and/or deformation. It also can impair patient's physical mobility, leading to mental discomfort and social isolation (Martín et al., 2011). Another adverse outcome can be an acute infection of the upper dermis and superficial lymphatics, caused by streptococcus bacteria. Today, the most common therapy consists of the following components; skin care, manual lymphatic drainage, bandaging and exercises (Brorson et al., 2008). Commonly used manual lymphatic drainage is time-consuming with no standardization among different physiotherapists (Tambour et al., 2014; Williams et al., 2002). Furthermore, the type of bandages used varies greatly. The scientific evidence as to what type of treatment or combination of treatments is most effective is scarce and/or controversial (Huang et al., 2013; Williams et al., 2002).
Even though very large numbers of people may be affected by chronic lymphedema, there is relatively little recognition of the seriousness of this chronic disease. However, it substantially increases postoperative medical costs for breast, prostate and cervical cancer survivors. In addition, up to ⅔ of obese individuals are thought to suffer from some aspects of lymphedema (Keast et al., 2014). As a result of improved cancer survival rates and the steadily growing number of overweight patients, the number of people who suffer from untreated or undertreated lymphedema has dramatically increased in recent years, particularly in Western societies. Yet, there is a limited arsenal of effective approaches to treat this debilitating condition. Patients' therapeutic options are few and new therapies to treat post-radiation lymphedema are critically needed.
There is a need for improved methods and devices to bring about improved drainage or directional flow of impaired venous blood or lymph.